Understanding the genetic mechanisms which underlie tumor development will provide a foundation for developing new generations of better and more effective cancer therapies. To address this fundamental issue, new technologies are needed that are superior to those currently available. Current state of the art mouse models enable testing the stochastic activation of oncogenes in a cell type specific fashion and provide a mechanism for testing targeted therapies. Despite these desirable features, their limited accessibility and feasibility precludes their implementation in most laboratories. Moreover, as the list of oncogenes continues to grow, reliable and efficient technologies are needed that can assess several oncogenes simultaneously in order to facilitate rapid analysis of tumorigenicity and their responses to therapy. This application provides a solution to all these issues by developing an innovative transgenic mouse platform (Crainbow) to rapidly, efficiently, and cost effectively create mouse models of tumorigenesis. The Crainbow technology will enable multiple user selectable oncogenes to be incorporated into a single transgenic mouse whereby each oncogene will be identifiable on the basis of a unique epitope tag and a separately expressed spectrally resolvable fluorescent protein. Using a strategy of Cre induced stochastic activation, the Crainbow technology enables the contribution of each oncogene to be assessed coincidentally in the same tissue with single cell resolution. Additionally, clonally derived tumor cell populations can be studied in any tissue and cell type by breeding to the plethora of validated cell type specific Cre mouse lines. Underlying the flexibility of this technology is a novel plasmid construct for incorporating the oncogenes of interest. The Crainbow plasmid can be easily modified for oncogene targeting using the molecular biology skills available in most all biology laboratories. Crainbow transgene mice can then be produced rapidly on site or obtained from other investigators or repositories. The utility and versatility of this Crainbow platform technology is demonstrated through the following specific aims which: (1) Establish a flexible and rapid strategy for cancer rainbow transgene design and construction, (2) Generate and validate cancer rainbow transgenic mice, & (3) Generate tissue specific tumors using cancer rainbow transgenic mice. The Cancer rainbow technology addresses in a single mouse shortcomings of current technology by providing a comprehensive method to simultaneously monitor the activity of multiple genes, and a means to also rapidly screen novel targeted cancer therapies. Consequently, the Cancer rainbow technology will provide a paradigm shift for studying tumorigenesis.